Crawler chassis roller assembly

Abstract

A tracked chassis roller assembly (17) comprising: a roller body (18) having an inner cavity (19) defined by a radially inner surface (20); a shaft (22) inserted into the inner cavity (19) of the roller body (18); a rolling bearing (36) comprising a single radially outer bearing ring (39), a first radially inner bearing ring (42), a second radially inner bearing ring (43), a first rolling element assembly (40) and a second rolling element assembly (41), wherein the first rolling element assembly (40) is radially interposed between the radially outer bearing ring (39) and the first radially inner bearing ring (42), and the second rolling element assembly (41) is radially interposed between the radially outer bearing ring (39) and the second radially inner bearing ring (43), wherein the radially outer bearing ring (39) is in contact with the radially inner surface (20) of the roller body (18), and wherein the first radially inner bearing ring (42) and the second radially inner bearing ring (43) are in contact with the shaft (22).

Description

Technical Field

[0001] This invention relates to a tracked chassis roller assembly. Background Technology

[0002] Tracked chassis are typically used to operate machinery such as earthmoving machinery, mining machinery, and crushing machinery, allowing the machinery to move on surfaces that are generally uneven or have poor traction.

[0003] Tracked chassis typically include two chain assemblies spaced apart and arranged parallel to each other, configured to receive drive torque and transmit it to the ground. Each chain assembly includes multiple chassis components, which typically include a closed-loop chain on the drive sprocket and an idler pulley (or intermediate gear) operably connected to a tensioner assembly. These chassis components further include multiple roller assemblies between the drive sprocket and the idler pulley, configured to guide the chain during movement. The roller assemblies typically include one or more upper roller assemblies and multiple lower roller assemblies.

[0004] Chains typically consist of multiple joints; the term joint refers to a single component of the chain that is hinged to other components. Typically, each joint comprises a pair of links facing each other. These joints are interconnected by pins. Each pin is typically inserted into a hole included in a link and connects the two joints together. A baseplate is usually mounted on the joints and is in direct contact with the ground, serving to release traction to the ground and increase the contact surface between the machine and the ground. The type of baseplate used depends on the ground on which the machine must operate, the environmental conditions under which the machine must operate, and the specifications recommended by the machine manufacturer.

[0005] Each roller assembly typically includes a roller body through which an axle passes. The roller assembly is defined by a radially inner surface facing the axle, and specifically, an outer surface facing the axle. The roller body is rotatable about the axle, which is fixed relative to a chassis frame and mounted on the frame.

[0006] During operation of the machine, the roller assembly is subjected to loads oriented parallel to and perpendicular to the axis. These loads are generated by the weight of the machine itself and the forces exchanged between the machine and the external environment. To ensure that the roller body rotates correctly relative to the corresponding axis and to transmit these loads between the roller body and the axis, the roller assembly is fitted with rolling bearings having tapered rollers with an axis inclined relative to the axis.

[0007] These tapered rolling bearings include a radially inner bearing ring (also called a cone), a radially outer bearing ring (also called a cup), and tapered rolling elements (also called rollers) having inclined axes of rotation between the cone and the cup and held by a cage that allows them to rotate freely about their respective axes of rotation. Typically, two axially spaced tapered rolling bearings are provided, wherein the respective rotating elements have corresponding axes of rotation converging toward the center point of the roller assembly.

[0008] Each tapered rolling bearing is fitted with a cone that contacts the shaft and a cup that contacts the radially inner surface of the roller body. The cup of each rolling bearing is inserted into the roller body via an interference fit with the radially inner surface until the cup is axially abutting against a corresponding shoulder on the radially inner surface of the roller body. A single cone with these associated rollers is mounted on the shaft, sliding along the shaft until it abuts against the shoulder on the shaft. The shaft is then inserted into the roller body such that the cone with the associated roller is received by the corresponding cup. Then, the cone and associated roller of another rolling bearing are slidably mounted onto the shaft until they reach and are received by the corresponding cup.

[0009] The cone and associated rollers need to be held axially, possibly with a small axial clearance (typically a few tenths of a millimeter), to prevent them from moving axially relative to the associated cup.

[0010] For this purpose, one or two threaded portions are provided on these shafts, each configured to receive an adjusting ring nut that acts axially (directly or via spacers) on the corresponding cone. By tightening or loosening the adjusting ring nut relative to the threaded portion of the shaft, the axial clearance of these cones can be adjusted to within a predetermined value. Once the adjusting ring nut has been adjusted, it is locked in place by a cotter pin or similar device to prevent movement during use of the roller assembly.

[0011] The resulting assembly is enclosed by two axial end supports, which are placed at the axial ends of the roller body and integrally formed with the shaft and chassis frame.

[0012] The applicant has noted that the assembly and maintenance of the roller body briefly described above may be complex and difficult to implement.

[0013] In fact, the applicant has noted that during the assembly of the roller assembly, special care must be taken to properly axially tighten the tapered rolling bearing by applying precise and careful action to the adjusting ring nut. Indeed, the applicant has demonstrated that errors of a fraction of a millimeter in tightening the adjusting ring nut can result in preload variations of up to two orders of magnitude (in kilograms) on the rolling bearing, causing near-immediate failure in the case of overtightening, or a significant reduction in the rolling bearing's service life of up to 80% in the case of insufficient tightening.

[0014] The applicant has also demonstrated that properly tightening these adjusting ring nuts is not only complex but also requires specialized workers, who may not be available during the manufacturing and initial installation of these roller assemblies, especially when the machine is being operated in remote and hard-to-reach areas.

[0015] The applicant has recognized that setting the axial clearance of these rolling bearings is advantageous when continuous or gradual adjustment of the adjusting ring nut is not required. In fact, the applicant has recognized that a precise and predetermined setting of the axial clearance of these rolling bearings will allow for easier and faster installation and maintenance of these rolling bearings.

[0016] Therefore, the applicant has assumed that a predetermined reference portion is provided for each rolling bearing for the shaft or roller body, which serves as an end stop for inserting the adjusting ring nut so as to bring the adjusting ring to a corresponding predetermined distance from the rolling bearing cone and obtain a predetermined and unique setting of the axial clearance of the rolling bearing.

[0017] However, the applicant has demonstrated that the precise axial distance between the two rolling bearing cones has an uncertainty given by the tolerance chain necessary for the production and assembly of the roller assembly.

[0018] In fact, the applicant has demonstrated that the manufacturing tolerance of rolling bearings typically used in roller assemblies is approximately 0.2 mm, meaning that the precise axial dimension of the rolling bearing cone (and cup) can be predetermined with an error of approximately 0.2 mm. Due to the manufacturing process of the shoulder and the press fit of the cup, the press fit of the shoulder adjacent to the roller body (i.e., inserting the cup into the roller body by interference fit) has a tolerance of approximately 0.05 mm. This tolerance chain must be considered relative to each rolling bearing, resulting in an uncertainty of at least 0.5 mm in the axial distance of the cones. Therefore, the applicant has estimated that the precise axial distance separating the two cones of these two rolling bearings is subject to an uncertainty of approximately 0.5 mm, resulting in any fixed reference portion or predetermined end stop for these adjusting rings not allowing the cones to be properly tightened and thus not allowing these rolling bearings and roller assemblies to function correctly. Summary of the Invention

[0019] This invention relates to a tracked chassis roller assembly, comprising:

[0020] A roller body having an inner cavity and a shaft, the inner cavity being defined by a radially inner surface, the shaft being inserted into the inner cavity of the roller body;

[0021] A rolling bearing includes a single radially outer bearing ring, a first radially inner bearing ring and a second radially inner bearing ring, a first rolling element assembly and a second rolling element assembly, wherein the first rolling element assembly is radially located between the radially outer bearing ring and the first radially inner bearing ring, and the second rolling element assembly is radially located between the radially outer bearing ring and the second radially inner bearing ring, wherein the radially outer bearing ring is in contact with the radially inner surface of the roller body, and wherein the first radially inner bearing ring and the second radially inner bearing ring are in contact with the shaft.

[0022] The applicant has recognized that by providing a roller assembly with a single rolling bearing having a single radial outer bearing ring (i.e., a single cup), two radial inner bearing rings (i.e., two cones) and two sets of rolling elements radially between the single cup and the two cones, the uncertainty of the actual axial distance of the cones is small enough to allow the use of end stops or fixed references to lock the axial clearance of the cones.

[0023] In fact, the applicant has recognized that in such rolling bearings, the axial length of a single cup, and therefore the nominal distance between the two cones, is affected by the manufacturing tolerances of the rolling bearing, which can be contained within a few hundredths of a millimeter, for example, within about 0.15 millimeters. In addition to this uncertainty, there is also an uncertainty in the position of the cones relative to the roller body, which is a few hundredths of a millimeter, for example, 0.05 millimeters.

[0024] Two radial inner bearing rings and two rolling element assemblies ensure the proper operation of the roller assembly by axially spacing the two rolling element assemblies (and therefore the two radial inner bearing rings) by a predetermined design distance, simply by providing radial upper bearing rings with corresponding axial dimensions.

[0025] A single radial outer bearing ring can be a single piece, i.e., made from a single body, or it can be made from two or more bodies joined together to form a single radial outer bearing ring.

[0026] The terms “axial,” “axially,” “radial,” and “radially” are used relative to the axis of rotation of the roller assembly.

[0027] Specifically, the terms "axial" and "axially" refer to a reference / quantity arranged / measured or extended in a direction parallel to or coinciding with the axis of rotation of the roller assembly.

[0028] The terms “radial” and “radially” refer to a reference / quantity arranged / measured or extended in a direction perpendicular to the axis of rotation of the roller assembly.

[0029] The terms "radial interior" and "radial exterior" refer to positions closer to or further away from the axis of rotation, respectively.

[0030] The terms “axial interior” and “axial exterior” refer to the locations of the roller assemblies that are closer to and further away from the axial ends of the shaft, respectively.

[0031] The term "press fit" refers to the engagement of two parts or components obtained by interference fit, wherein the two parts or components are constrained to each other in terms of rotation and translation.

[0032] In some designs, the radial outer bearing ring is inserted into the radial inner surface of the roller body via an interference fit. This connection allows the bearing ring to be radially constrained to the outside of the roller body.

[0033] In some designs, two radial inner bearing rings are inserted into the shaft via an interference fit.

[0034] The applicant has discovered that by press-fitting the outer radial ring into the roller body and the inner radial bearing ring onto the shaft, any adjusting ring nut can be eliminated, and the use of end stops or fixed references to lock the axial clearance of the inner radial bearing ring can be avoided.

[0035] In fact, the applicant has realized that a single rolling bearing can first be press-fitted onto the shaft (by pressing the radial inner bearing ring onto the shaft), and then the assembly given by the shaft and the rolling bearing can be inserted into the roller body by pressing the rolling bearing (in particular the radial outer bearing ring) into the roller body.

[0036] In some embodiments, the radial outer bearing ring is not anchored in the roller body, but is slidably inserted into the inner cavity of the roller body, wherein the outer surface of the radial outer bearing ring contacts the radial inner surface of the roller body.

[0037] In some embodiments of the invention, the roller body includes a first annular recess along a radially inner surface; a stop ring is inserted into the first annular recess and the stop ring acts on a radially outer bearing ring.

[0038] The radial outer bearing ring is preferably pressed against a stop ring that provides an end stop, or regardless of the reference portion used for positioning the radial outer bearing ring relative to the roller body, whether the radial inner bearing ring is press-fitted into the roller body or slidably inserted into the roller body.

[0039] In some embodiments of the invention, the roller body includes a second annular recess along a radially inner surface; a stop ring is inserted into the second annular recess and the stop ring acts on a radially outer bearing ring from a portion opposite to the stop ring inserted in the first recess.

[0040] The radial outer bearing ring preferably presses against a stop ring, which provides an end stop, regardless of the reference portion in which the radial outer bearing ring is positioned relative to the roller body. A second annular recess and a corresponding stop ring are preferably provided when the radial outer bearing ring is not anchored in the roller body.

[0041] In some embodiments of the invention, the roller body includes a shoulder disposed on a radially inner surface; a radially outer bearing ring abuts against the shoulder. The shoulder is preferably disposed when the radially outer bearing ring is press-fitted into the roller body, and the shoulder serves as an end stop when the radially outer bearing ring is inserted into the roller body.

[0042] In some embodiments of the present invention, a shoulder may be provided on the radial inner surface of the roller body, and an annular recess and a stop ring inserted into the recess may be provided in axially opposite positions.

[0043] In some embodiments of the invention, the shaft includes a first annular recess along its radially outer surface; a stop ring is inserted into the first annular recess and the stop ring acts on a second radially inner bearing ring.

[0044] The second radial inner bearing ring preferably abuts against a stop ring that provides a reference for positioning the second radial inner bearing ring relative to the shaft, regardless of whether the second radial inner bearing ring is press-fitted onto the shaft or mounted on the shaft.

[0045] In some embodiments, the shaft includes a second annular recess along its radially outer surface; a stop ring is inserted into the second annular recess and the stop ring acts on a first radially inner bearing ring.

[0046] The first radial inner bearing ring preferably abuts against the stop ring, which provides a reference portion for positioning the first radial inner bearing ring relative to the shaft, regardless of whether the second radial inner bearing ring is press-fitted onto the shaft or mounted on the shaft.

[0047] In some embodiments of the invention, the radial inner bearing ring is slidably inserted into the shaft. In these embodiments, the radial inner bearing ring is not press-fitted onto the shaft, but rather assembled onto the radial outer surface of the shaft without an interference fit. In these embodiments, it is conceivable that the rolling bearing is first constrained to the roller body, the shaft is inserted into the inner cavity of the roller body, and the rolling bearing is axially locked relative to the shaft.

[0048] Preferably, when the first recess and the second recess are provided on the radial outer surface of the shaft, the rolling bearing is assembled on the shaft but not press-fitted onto the shaft.

[0049] Preferably, the roller body includes a first axial end and a second axial end opposite to the first axial end.

[0050] Preferably, the rolling bearing acts between a first region of the inner cavity of the roller body and a second region of the inner cavity of the roller body, wherein the first region is axially closer to the first axial end of the roller body relative to the second axial end, and the second region is axially closer to the second axial end of the roller body relative to the first axial end.

[0051] In other words, the rolling bearing preferably extends in the central region of the roller assembly, that is, in the region that is positioned approximately centrally relative to the first and second axial ends of the roller body.

[0052] Preferably, the radial inner surface of the roller body is cylindrical between the first and second regions of the inner cavity.

[0053] Therefore, the radial outer bearing ring of the rolling bearing can be made into a cylindrical shape and can be easily connected to the radial inner surface of the roller body.

[0054] Preferably, the inner cavity has a radial extension between the second region and the second axial end of the roller body, the radial extension being equal to or greater than the extension of the inner cavity between the first region and the second region.

[0055] Therefore, the radial outer bearing ring or the entire rolling bearing can be inserted into the roller body through the second axial end of the roller body.

[0056] Preferably, the shaft includes a central portion extending between a first region and a second region within the inner cavity of the roller body. A first radial inner bearing ring and a second radial inner bearing ring are disposed within the central portion of the shaft.

[0057] Preferably, the central portion of the shaft has a radially outer cylindrical surface with a constant diameter. Thus, the radially inner bearing ring can be made cylindrical and can be easily coupled to the radially outer surface of the central portion of the shaft.

[0058] Preferably, the shaft includes a first axial end and a second axial end.

[0059] Preferably, the radial outer surface of the shaft is cylindrical between the central portion and the second end, and its diameter is equal to or less than the diameter of the central portion.

[0060] Thus, the radial inner bearing ring or the entire rolling bearing can be inserted into the shaft through the second end of the shaft and reach the center portion.

[0061] Preferably, the roller body includes a central body, a first axial end flange and a second axial end flange located at corresponding axial ends of the central body; the central body defines the inner cavity of the roller body.

[0062] The first flange and the second flange are preferably connected to the central body and enclose the inner cavity of the roller body.

[0063] Preferably, a hydraulic seal is provided between each flange and the shaft, the hydraulic seal being configured to allow relative rotation between the roller body and the shaft and to liquidally seal the inner cavity.

[0064] Preferably, the inner cavity is filled with oil or grease to cool or otherwise lubricate the rolling bearing.

[0065] The central body can be made into one piece or it can be made from two halves joined together.

[0066] In some embodiments of the invention, the first flange and the central body are a single piece. In these embodiments, the second flange is permanently connected to the assembly provided by the central body and the first flange. Attached Figure Description

[0067] Other features and advantages of the invention will become more apparent from the following description of preferred embodiments of the invention with reference to the accompanying drawings. In these drawings:

[0068] - Figure 1 This is a schematic side view of a tracked chassis;

[0069] - Figure 2 According to the present invention and the first embodiment Figure 1 A schematic cross-sectional view of the roller assembly of a tracked chassis;

[0070] - Figure 3 According to the second embodiment Figure 1 A schematic cross-sectional view of the roller assembly of a tracked chassis;

[0071] - Figure 4 According to the third embodiment Figure 1 A schematic cross-sectional view of the roller assembly of the tracked chassis; and

[0072] - Figure 5 According to the fourth embodiment Figure 1 A schematic cross-sectional view of the roller assembly of a tracked chassis. Detailed Implementation

[0073] Figure 1 This is a schematic side view showing some components of a tracked chassis. The tracked chassis 10 includes two track assemblies 11, in... Figure 1Only one track assembly is visible in the figure. Each track assembly 11 includes a chain 12, a return wheel 14, and a drive wheel 16. The chain 12 includes multiple links 13 interconnected by pins and bushings (not shown). The return wheel 14 is partially hidden by the crankcase 15 in the figure. Multiple roller assemblies 17 are arranged between the return wheel 14 and the drive wheel 16. Specifically, one or more upper roller assemblies and multiple lower roller assemblies are arranged to contact the links 13 and be adapted to guide the movement of the chain 12.

[0074] The lower roller assembly 17 is arranged in the lower part of the track assembly 11 and is configured to transmit load between the track and the chassis frame (not shown). The upper roller assembly 17 is configured to guide the chain between the drive wheel 16 and the return wheel 14, and is generally present in fewer numbers than the lower roller assemblies. The number of lower roller assemblies 17 varies depending on the type and weight of the machine.

[0075] Reference Figures 2 to 5 The figures preferably illustrate some preferred embodiments of the lower roller assembly 17 according to the invention. The same reference numerals denote the same features in each embodiment, and the differences between them will be apparent hereinafter.

[0076] Figures 2 to 5 This is a cross-sectional view of the lower roller assembly 17. The cross-section is a longitudinal plane that is transverse to the chain link 13 of the chain 12 and therefore transverse to the direction of movement of the tracked chassis, passing through the axis of rotation X of the roller assembly 17.

[0077] The roller assembly 17 includes a roller body 18, which includes an inner cavity 19 extending from a first axial end 18a to a second axial end 18b.

[0078] The roller body 18 is defined by a radial inner surface 20 and a radial outer surface 21. The radial inner surface 20 defines an inner cavity 19 in the radial outer direction. The shape of the radial outer surface 21 is determined by the type of chain 12. The roller assembly 17 must interact with the chain 12.

[0079] The roller body 18 is preferably made of low-alloy steel, which is boron alloyed and subjected to at least one heat treatment. Low-alloy steel is steel in which elements other than iron and carbon are present and in which these other elements are not present in amounts exceeding 5%.

[0080] The roller assembly 17 also includes a shaft 22 inserted into the cavity 19 of the roller body 18. The shaft 22 extends between a first axial end 22a and a second axial end 22b and has a radially outer surface 23 facing the radially inner surface 20 of the roller body 18.

[0081] Shaft 22 is preferably made of low alloy steel that has undergone at least one heat treatment with boron alloy or micro alloy steel that does not require any heat treatment.

[0082] The axial extension of shaft 22 is greater than the axial extension of roller body 18. In other words, the axial distance between the first axial end 22a and the second axial end 22b of shaft 22 is greater than the distance measured along the same direction between the first axial end 18a and the second axial end 18b of roller body 18.

[0083] Shaft 22 extends axially beyond the first axial end 18a and the second axial end 18b of roller body 18. Specifically, the axial extension of shaft 22 beyond the first axial end 18a of roller body 18 is approximately equal to the axial extension of shaft 22 beyond the second axial end 18b of roller body 18.

[0084] The shaft portion 22 extending outward from the first axial end 18a of the roller body 18 is integral with the chassis frame or with the chassis component, wherein the chassis component is integral with the chassis frame.

[0085] For this purpose, a support member 24 is provided (in Figures 2 to 5 (shown schematically in the diagram) The support member 24 is integrally formed with the chassis frame or with the chassis component. The chassis component is integral with the chassis frame. The chassis frame is provided with an internal cavity 25. The shaft portion 22 is inserted into the internal cavity 25. The shaft portion 22 extends outward in the axial direction from the first axial end 18a of the roller body 18.

[0086] To integrate shaft 22 with support 24, shaft 22 may include a radial cavity (not shown) intersecting shaft 22 in the radial direction. Two radially opposing through holes are formed in support 24, which can be aligned between themselves and with the radial cavity of shaft 22. A plug (not shown) can be inserted into the radial cavity such that it passes through the radial cavity and seals the two through holes of support 24. This prevents any axial movement and rotation of shaft 22 relative to support 24 about the axis of rotation X.

[0087] Similarly, the shaft portion 22 extending outward from the second axial end portion 18b of the roller body 18 is integrally formed with the chassis frame or with the chassis component via a similar support member 24, wherein the chassis component is integral with the chassis frame.

[0088] The roller body 18 is mounted so that it can rotate about the rotation axis X relative to the shaft 22.

[0089] The roller body 18 includes a central body 26, which faces directly into the inner cavity 19. The radial inner surface 20 of the roller body 18 is on the inner cavity 19. The central body 26 has an axial end 27.

[0090] The central body 26 can be made as a single piece, or more preferably, obtained by welding or by connecting two halves through an interference fit (not shown).

[0091] Figure 2 The central body 26 is schematically shown as being made of two halves 26a, 26b, which are joined together to form a single body.

[0092] At one axial end 27 of the central body 26, the roller body 18 includes a first axial end flange 28, and at the other axial end 27 of the central body 26, the roller body 18 includes a second axial end flange 29.

[0093] The first axial end flange 28 and the second axial end flange 29 are both integral with the central body 26, that is, they rotate together with the central body 26 around the axis X.

[0094] A first axial end flange 28 and a second axial end flange 29 extend radially to the shaft 22. Specifically, the first flange 28 includes a radially inner surface 30 directly facing the shaft 22. Similarly, the second flange 29 includes a radially inner surface 31 directly facing the shaft 22.

[0095] The inner cavity 19 is closed in the axial direction at the first flange 28 by a hydraulic sealing member 32 located between the radial inner surface 30 of the first flange 28 and the shaft 22. This hydraulic sealing member 32 can be an O-ring inserted into an annular sealing groove 33 on the shaft 22, such as... Figures 2 to 4 As shown in the embodiments. Alternatively, this hydraulic sealing member 32 can be a rotary hydraulic box seal mounted on the shaft 22 and acting on the radially inner surface 30, such as Figure 5 The example is schematically shown. Alternatively, this hydraulic sealing member 32 may be a lip gasket (not shown) acting between the shaft 22 and the radially inner surface 30 of the first flange 28.

[0096] The inner cavity 19 is closed in the axial direction at the second flange 29 by a hydraulic sealing member 34 located between the radial inner surface 31 of the second flange 29 and the shaft 22. This hydraulic sealing member 34 can be an O-ring inserted into an annular sealing groove 35 on the shaft 22, such as... Figures 2 to 4 As shown in the embodiment. Alternatively, this hydraulic sealing member 34 can be a rotary hydraulic box seal mounted on the shaft 22 and acting on the radially inner surface 31, such as Figure 5The example is schematically shown. Alternatively, this hydraulic sealing member 34 may be a lip gasket (not shown) acting between the shaft 22 and the radially inner surface 31 of the second flange 29.

[0097] In all embodiments of the invention, the roller assembly 17 includes a rolling bearing 36 that is inserted into the inner cavity 19 and acts between the shaft 22 and the radial inner surface 20 of the roller body 18.

[0098] Preferably, only one rolling bearing 36 is provided.

[0099] The rolling bearing 36 extends between a first region 37 located axially near a first axial end 18a of the roller body 18 in the inner cavity 19 and a second region 38 located axially near a second axial end 18b of the roller body 18 in the inner cavity 19. The first region 37 is also closer to the first axial end 18a than it is to the second axial end 18b, and the second region 38 is closer to the second axial end 18b than it is to the first axial end 18a. The first region 37 of the inner cavity 19 is radially located in the portion of the inner cavity 19 between the central body 26 and the shaft 22 of the roller body 18, and is not affected by the rolling bearing 36. The first region 37 is axially located between the first flange 28 and the rolling bearing 36. The second region 38 of the inner cavity 19 is radially located in the portion of the inner cavity 19 between the central body 26 and the shaft 22 of the roller body 18, and is not affected by the rolling bearing 36. The second region 38 is axially located between the second flange 29 and the rolling bearing 36.

[0100] like Figures 2 to 4 As shown, the rolling bearing 36 is placed at the center portion 22c of the shaft 22, and the center portion 22c is located between the first axial end 22a and the second axial end 22b.

[0101] The rolling bearing 36 is unique, that is, preferably, only one rolling bearing 36 exists in the drive roller assembly 17, between the shaft 22 and the radial inner surface 20 of the roller body 18.

[0102] The rolling bearing 36 includes a single radial outer bearing ring 39 (or cup), a first rolling element assembly 40 and a second rolling element assembly 41, a first radial inner bearing ring 42 (or a first cone) and a second radial inner bearing ring 43 (or a second cone).

[0103] The first rolling element assembly 40 is radially positioned between the radial outer bearing ring 39 and the first radial inner bearing ring 42 and acts directly on them.

[0104] The second rolling element assembly 41 is radially positioned between the radial outer bearing ring 39 and the second radial inner bearing ring 43 and acts directly on them.

[0105] The first rolling element assembly 40 includes a plurality of circumferentially arranged spheres, or more preferably barrel-shaped or truncated conical rollers. The first rolling element assembly 40 includes a first axial end 40a having a diameter larger than that of the second axial end 40b. Similarly, the second rolling element assembly 41 includes a plurality of circumferentially arranged spheres, or more preferably barrel-shaped or truncated conical rollers. The rolling element 41 includes a first axial end 41a having a diameter larger than that of the second axial end 41b.

[0106] The second axial end 40b of the rolling element of the first rolling element assembly 40 faces the second axial end 41b of the rolling element of the second rolling element assembly 41.

[0107] The rolling axis A1 of the first rolling element assembly 40 is inclined relative to the rotation axis X, just as the rolling axis A2 of the second rolling element assembly 41 is inclined relative to the rotation axis X.

[0108] In a preferred embodiment of the invention, the rolling axes A1 and A2 of the two rolling element assemblies 40 and 41 are inclined such that the first axial end 40a of the rolling element of the first rolling element assembly 40 is positioned further radially away from the rotation axis X relative to the second axial end 40b of the rolling element of the first rolling element assembly 40, and the first axial end 41a of the rolling element of the second rolling element assembly 41 is positioned further radially away from the rotation axis X relative to the second axial end 41b of the rolling element of the second rolling element assembly 41.

[0109] In an alternative embodiment not shown, the rolling axes A1 and A2 of the two rolling element assemblies 40 and 41 are inclined such that the first axial end 40a of the rolling element of the first rolling element assembly 40 is radially closer to the rotation axis X relative to the second axial end 40b of the rolling element of the first rolling element assembly 40, and the first axial end 41a of the rolling element of the second rolling element assembly 41 is radially closer to the rotation axis X relative to the second axial end 41b of the rolling element of the second rolling element assembly 41.

[0110] The extension of the outer radial bearing ring 39 in the axial direction is at least equal to the sum of the radial extensions of the first inner radial bearing ring 42 and the second inner radial bearing ring 43, and preferably it is greater than the sum of the radial extensions of the first inner radial bearing ring 42 and the second inner radial bearing ring 43.

[0111] Between the first radial inner bearing ring 42 and the second radial inner bearing ring 43, a closing ring 44 is axially arranged to close the lubrication cavity 45 of the rolling bearing 36, and the lubrication cavity 45 is preferably filled with oil or grease.

[0112] In all embodiments, the radially inner surface 20 of the roller body is cylindrical at the radially outer bearing ring 39 of the rolling bearing 36. The radially outer bearing ring 39 is also cylindrical at its radially outer surface 39a, so as to be shaped relative to the portion of the radially outer surface 20 of the roller body 18 that receives the radially outer bearing ring 39.

[0113] In a preferred embodiment of the invention, the rolling bearing 36 may be pre-assembled. The pre-assembled rolling bearing is envisioned in which a first radially inner bearing ring 42 and a second radially inner bearing ring 43 are operatively associated with a radially outer bearing ring 39, wherein a first rolling element assembly 40 and a second rolling element assembly 41 are respectively radially inserted between the first radially inner bearing ring 42 and the radially outer bearing ring 39, and between the second radially inner bearing ring 43 and the radially outer bearing ring 39. In the pre-assembled rolling bearing, the closing ring 44 is also in the operative position.

[0114] The diameter of the inner cavity 19 is constant at the radially inner surface portion 20 of the roller body 18, which receives the radially outer bearing ring 39 of the rolling bearing 36. Between the second region 38 of the inner cavity 19 and the second axial end 18b of the roller body, the inner cavity 19 has a generally cylindrical shape, with a diameter equal to or greater than the diameter at the radially outer bearing ring 39 of the rolling bearing 36. Therefore, between the second region 38 of the inner cavity 19 and the second axial end 18b of the roller body, the diameter of the inner cavity 19 is equal to or greater than the maximum radial dimension of the rolling bearing 36.

[0115] The central portion 22c of shaft 22 has a cylindrical radially outer surface 22d with a constant diameter. The first radially inner bearing ring 42 and the second radially inner bearing ring 43 have corresponding annular radially inner surfaces 42a and 43a, whose minimum diameters approximately correspond to the diameter of the central portion 22c of shaft 22.

[0116] Between the second axial end 22b and the central portion 22c, the shaft 22 has an extension in the radial direction whose size is equal to or smaller than the diameter of the central portion 22c. Similarly, between the first axial end 22a and the central portion 22c, the shaft 22 has an extension in the radial direction whose size is equal to or smaller than the diameter of the central portion 22c.

[0117] exist Figure 2 In the embodiment shown, the radial outer bearing ring 39 of the rolling bearing 36 is press-fitted onto the radial inner surface 20 of the roller body 18.

[0118] In this embodiment, the roller body 18 includes a shoulder 46 configured to project radially inward from the radially inner surface 20. The shoulder serves as a stop for inserting the radially outer bearing ring 39 into the roller body 18. In this embodiment, a first radially inner bearing ring 42 and a second radially inner bearing ring 43 are press-fitted onto the shaft 22. To achieve this connection, the rolling bearing 36 is first assembled (or pre-assembled) and press-fitted onto the shaft 22, thereby applying an axial thrust to the second radially inner bearing ring 43, which is transmitted to the first radially inner bearing ring 42 via a closing ring 44. When the rolling bearing reaches the desired position on the shaft 22, the assembly of the shaft 22 and the rolling bearing 36 is introduced from the side of the second axial end portion 18b of the roller body 18 into the cavity 19. In this step, the second flange 29 is decoupled from the central body 26 of the roller body 18. The rolling bearing 36 is pressed into the radial inner surface 20 of the roller body 18 by means of the axial thrust on the radial outer ring 39 until the rolling bearing 36 reaches the shoulder 46 and abuts against the shoulder 46. At this time, the second flange 29 can be constrained to the center body 26 of the roller body 18. At this time, the first flange 28 is also constrained to the center body 26 of the roller body 18.

[0119] exist Figure 2 In this embodiment, the first flange 28 is separate from the central body 26 of the roller body 18, and is also constrained to the central body 26. The space in the inner cavity 19 not occupied by the rolling bearing 36 may be filled with oil or grease.

[0120] Also in Figure 3 In the embodiment shown, the radial outer bearing ring 39 of the rolling bearing 36 is press-fitted onto the radial inner surface 20 of the roller body 18.

[0121] and Figure 2 The difference in the embodiments is that the first radial inner bearing ring 42 and the second radial inner bearing ring 43 can be press-fitted onto the shaft 22 or can be inserted into the shaft 22 and can move axially relative to the shaft 22.

[0122] In this embodiment, the shaft 22 includes a first annular recess 47 on its radially outer surface. This first recess 47 is positioned at the beginning of the second region 38 of the inner cavity 19. In other words, the first recess 47 is axially positioned at the outermost axial position occupied by the second radially inner bearing ring 43. A stop ring 48 is inserted into the first recess 47, serving as an axial abutment of the second radially inner bearing ring 43. The stop ring 48 can be inserted into the first recess 47 and (if necessary) can be removed from the first recess 47, and can be, for example, a seeger ring.

[0123] The shaft 22 further includes a second annular recess 49 on its radially outer surface. This second recess 49 is positioned at the beginning of the first region 37 of the inner cavity 19. In other words, the second recess 49 is axially positioned at the outermost axial position occupied by the first radially inner bearing ring 42. A stop ring 50 is inserted into the second recess 49, serving as an axial abutment of the second radially inner bearing ring 43. The stop ring 50 can be inserted into the second recess 49 and (if necessary) can be removed from the second recess 49, and can be, for example, a SIG ferrule.

[0124] To accommodate the rolling bearing 36, if the rolling bearing 36 is pre-assembled and the radial inner bearing rings 42, 43 are press-fitted onto the shaft 22, the rolling bearing 36 is press-fitted onto the shaft 22, thereby applying an axial thrust to the second radial inner bearing ring 43, which is transmitted to the first radial inner bearing ring 42 through the closing ring 44. On the shaft 22, a stop ring 50 is pre-inserted into the second recess 49. When the rolling bearing reaches the stop ring on the shaft 22, the stop ring 48 is inserted into the first recess 48, further axially locking the rolling bearing 36 onto the shaft 22 (in addition to the locking provided by the press fit). The assembly of the shaft 22 and the rolling bearing 36 is introduced into the cavity 19 from the side of the second axial end 18b of the roller body 18. In this step, the second flange 29 is decoupled from the central body 26 of the roller body 18. The rolling bearing 36 is pressed into the radial inner surface 20 of the roller body 18 by means of the axial thrust on the radial outer ring 39 until the rolling bearing 36 reaches and abuts against the shoulder 46. At this time, the second flange 29 can be constrained to the center body 26 of the roller body 18. At this time, the first flange 28 is also constrained to the center body 26 of the roller body 18.

[0125] With the rolling bearing 36 pre-assembled and the radial inner bearing rings 42 and 43 not mounted on the shaft 22, the radial outer bearing ring 39 is mounted on the radial inner surface 20 of the roller body 18. The bearing ring 39 is axially press-fitted onto the radial inner surface 20 of the roller body 18 until the radial outer bearing ring 39 reaches and abuts against the shoulder 46. Next, the stop ring 48 is inserted into the first recess 47 of the shaft 22. Then, the shaft 22 is introduced from the side of the second axial end 18b of the roller body 18 into the inner recess 19 until the stop ring 48 axially contacts the second radial inner bearing ring 43. In this step, the shaft 22 slides axially relative to the rolling bearing 36 without interference. At this time, the stop ring 50 is inserted into the second recess 49, thereby axially locking the shaft 22 and the rolling bearing 22. At this time, the first flange 28 and the second flange 29 are constrained to the center body 26 of the roller body 18.

[0126] If the rolling bearing 36 is not pre-assembled, the outer radial bearing ring 39 first presses against the inner radial surface 20 of the roller body 18 until it axially abuts against the shoulder 46. Then, the shaft 22 is inserted into the roller body 18. At this time, the first inner radial bearing ring 42 is inserted onto the shaft 22 together with the first rolling element assembly 40, and the first inner radial bearing ring 42 slides axially against the assembly of the first rolling element assembly 40 until it reaches and engages with the outer radial bearing ring 39. A closing ring 44 is inserted onto the shaft 22, axially abutting against the first inner radial bearing ring 42. Next, the second inner radial bearing ring 43 and the second rolling element assembly 41 are inserted onto the shaft 22, and the second inner radial bearing ring 43 and the second rolling element assembly 41 slide axially until they reach and abut against the closing ring 44, such that the second inner radial bearing ring 43 and the second rolling element assembly 41 reach and abut against the outer radial bearing ring 39. At this point, the stop ring 48 is inserted into the first recess 47, making it contact the second radial inner bearing ring 43. After the second radial inner bearing ring 43 has been inserted into the shaft 22, or before the second radial inner bearing ring 43 is inserted into the shaft, the stop ring 50 is inserted into the second recess 49. At this point, the first flange 28 and the second flange 29 are constrained to the center body 26 of the roller body 18.

[0127] exist Figure 4 In the illustrated embodiment, the roller body 18 includes a first annular recess 51 on the radially inner surface 20. This first recess 51 is positioned at the beginning of a first region 37 of the cavity 19. In other words, the first recess 51 is axially positioned at the outermost axial position occupied by the radially outer bearing ring 39. Within the first recess 51 is a stop ring 52, which serves as an axial contact for the radially outer bearing ring 39. The stop ring 52 can be inserted into the first recess 51 and (if necessary) can be removed from the first recess 51, and can be, for example, a Sieg retainer ring.

[0128] The roller body 18 further includes a second annular recess 53 on the radially outer surface 20. This second recess 53 is positioned at the beginning of the second region 38 of the inner cavity 19. In other words, the second recess 53 is axially positioned at the outermost axial position on the opposite side of the first recess 51, occupied by the radially outer bearing ring 39. A stop ring 54 is inserted into the second recess 53, serving as an axial contact for the radially outer bearing ring 39. The stop ring 54 can be inserted into the second recess 53 and (if necessary) can be removed from the second recess 53, and can be, for example, a SIG guard ring.

[0129] Such as about Figure 3 As described in the embodiments, the shaft 22 includes a first annular recess 47, a second annular recess 49, and corresponding stop rings 48 and 50.

[0130] This embodiment is similar to Figure 3 The difference between the embodiments shown is that the radial outer bearing ring 39 can be press-fitted into the roller body 18 or can be slidably inserted into the roller body 18.

[0131] If the rolling bearing 36 is pre-assembled, the outer radial bearing ring 39 is press-fitted into the roller body 18 and the inner radial bearing rings 42 and 43 are press-fitted onto the shaft 22, thereby applying an axial thrust to the second inner radial bearing ring 43, which is transmitted to the first inner radial bearing ring 42 via the closing ring 44. On the shaft 22, a stop ring 50 is pre-inserted into the second recess 49. When the rolling bearing reaches the stop ring on the shaft 22, the stop ring 48 is inserted into the first recess 48, thereby further axially locking the rolling bearing 36 onto the shaft 22 (in addition to the locking provided by the press fit). The assembly of the shaft 22 and the rolling bearing 36 is introduced into the cavity 19 from the side of the second axial end 18b of the roller body 18. In this step, the second flange 29 is decoupled from the central body 26 of the roller body 18. The rolling bearing 36 is press-fitted onto the radial inner surface 20 of the roller body 18 by applying an axial thrust to the radial outer bearing ring 39 until the radial outer bearing ring 39 reaches the stop ring 52 (pre-inserted into the first recess 51 of the roller body 18) and abuts against the stop ring 52. Then, the stop ring 54 is inserted into the second recess 53 of the roller body 18, thereby axially locking the rolling bearing 36 relative to the roller body 18 (in addition to the locking provided by the press fit). At this time, the second flange 29 can be constrained to the center body 26 of the roller body 18. At this time, the first flange 28 is also constrained to the center body 26 of the roller body 18.

[0132] If the rolling bearing 36 is pre-assembled, the outer radial bearing ring 39 is press-fitted into the roller body 18 and the inner radial bearing rings 42, 43 are slidably inserted into the shaft 22, with the outer radial bearing ring 39 press-fitted onto the inner radial surface 20 of the roller body 18. The outer radial bearing ring 39 is press-fitted onto the inner radial surface 20 of the roller body 18 by applying an axial thrust to the outer radial bearing ring 39 until it reaches and abuts against the stop ring 52 (pre-inserted into the first recess 51 of the roller body 18). Then, the stop ring 54 is inserted into the second recess 53 of the roller body 18, thereby axially locking the rolling bearing 36 relative to the roller body 18 (in addition to the locking provided by the press fit). Next, the stop ring 48 is inserted into the first recess 47 of the shaft 22. Then, the shaft 22 is introduced from the side of the second axial end 18b of the roller body 18 into the recess 19 until the stop ring 48 makes axial contact with the second radial inner bearing ring 43. In this step, the shaft 22 slides axially relative to the rolling bearing 36 without interference. At this time, the stop ring 50 is inserted into the second recess 49, thereby axially locking the shaft 22 and the rolling bearing 22. At this time, the first flange 28 and the second flange 29 are constrained to the center body 26 of the roller body 18.

[0133] If the rolling bearing 36 is pre-assembled, the outer radial bearing ring 39 is slidably inserted into the roller body 18 and the inner radial bearing rings 42 and 43 are slidably inserted into the shaft 22. The outer radial bearing ring 39 is slidably inserted into the roller body 18 until it reaches the stop ring 52 (pre-inserted into the first recess 51 of the roller body 18) and abuts against the stop ring 52. Then, the stop ring 54 is inserted into the second recess 53 of the roller body 18, thereby axially locking the rolling bearing 36 relative to the roller body 18. Next, the stop ring 48 is inserted into the first recess 47 of the shaft 22. Then, the shaft 22 is introduced from the side of the second axial end 18b of the roller body 18 into the inner recess 19 until the stop ring 48 axially contacts the second inner radial bearing ring 43. In this step, the shaft 22 slides axially relative to the rolling bearing 36 without interference. At this time, the stop ring 50 is inserted into the second recess 49, thereby axially locking the shaft 22 and the rolling bearing 22. At this time, the first flange 28 and the second flange 29 are constrained to the center body 26 of the roller body 18.

[0134] Alternatively, the stop ring 48 is inserted into the first recess 47 of the shaft 22. Then, the rolling bearing 36 is slidably inserted into the shaft 22 until it abuts against the stop ring 48. At this point, the stop ring 50 is inserted into the second recess 49, thereby axially locking the shaft 22 and the rolling bearing 22. The assembly of the shaft 22 and the rolling bearing 36 is slidably inserted into the roller body 18 until the radially outer bearing ring 39 reaches the stop ring 52 (pre-inserted into the first recess 51 of the roller body 18) and abuts against it. Then, the stop ring 54 is inserted into the second recess 53 of the roller body 18, thereby axially locking the rolling bearing 36 relative to the roller body 18. At this point, the first flange 28 and the second flange 29 are constrained to the center body 26 of the roller body 18.

[0135] Figure 5 The embodiments provide information about Figure 3 The same operation is described in the embodiment, except that the first flange 28 and the center body 26 of the roller body 18 are a single piece.

[0136] Those skilled in the art will recognize that various features of the above embodiments can be combined to obtain other embodiments, all of which fall within the scope of protection of the invention as defined by the appended claims.

Claims

1. A tracked undercarriage roller assembly (17) comprising: - a roller body (18) having an inner cavity (19) delimited by a radial inner surface (20) and a shaft (22) inserted into the inner cavity (19) of the roller body (18); - a rolling bearing (36) comprising a single radial outer bearing ring (39), a first radial inner bearing ring (42), a second radial inner bearing ring (43), a first rolling element assembly (40) radially interposed between the radial outer bearing ring (39) and the first radial inner bearing ring (42), and a second rolling element assembly (41) radially interposed between the radial outer bearing ring (39) and the second radial inner bearing ring (43), wherein the radial outer bearing ring (39) is in contact with the radial inner surface (20) of the roller body (18) and wherein the first radial inner bearing ring (42) and the second radial inner bearing ring (43) are in contact with the shaft (22), - wherein the shaft (22) comprises a first annular recess (47) along a radial outer surface (22d) of the shaft (22); a first stop ring (48) is inserted into the first annular recess (47) and acts on the second radial inner bearing ring (43), - wherein the shaft (22) comprises a second annular recess (49) along the radial outer surface (22d) of the shaft (22); a second stop ring (50) is inserted into the second annular recess (49) and acts on the first radial inner bearing ring (42).

2. The track chassis roller assembly (17) of claim 1, wherein, - the roller body (18) comprises a first axial end (18a) and a second axial end (18b) opposite to the first axial end (18a); the rolling bearing (36) acts between a first zone (37) of the inner cavity (19) of the roller body (18) axially closer to the first axial end (18a) of the roller body (18) with respect to the second axial end (18b) and a second zone (38) of the inner cavity (19) of the roller body (18) axially closer to the second axial end (18b) of the roller body (18) with respect to the first axial end (18a).

3. The track chassis roller assembly (17) of claim 2, wherein, - the radial inner surface (20) of the roller body (18) is cylindrical between the first zone (37) and the second zone (38); the inner cavity (19) has a radial extension between the second zone (38) and the second axial end (18b) of the roller body (18) equal to or higher than the extension of the inner cavity (19) between the first zone (37) and the second zone (38).

4. The track chassis roller assembly (17) of claim 2 or 3, wherein, The shaft (22) includes a central portion (22c) extending between the first region (37) and the second region (38) of the inner cavity (19) of the roller body (18); the central portion (22c) of the shaft (22) has a radial outer surface (22d) which is a cylindrical shape with a constant diameter.

5. The track chassis roller assembly (17) of any of claims 1-3, wherein, The roller body (18) includes a central body (26), a first axial end flange (28) and a second axial end flange (29), the first axial end flange (28) and the second axial end flange (29) being located at the corresponding axial ends (27) of the central body (26); the central body (26) defines the inner cavity (19) of the roller body (18).

6. The track chassis roller assembly (17) of claim 5, wherein, The first axial end flange (28) is integral with the central body (26).

7. The track chassis roller assembly (17) of any one of claims 1-3, wherein, The radial outer bearing ring (39) is inserted into the radial inner surface (20) of the roller body (18) by an interference fit.

8. The track chassis roller assembly (17) of any one of claims 1-3, wherein, The first radial inner bearing ring (42) and the second radial inner bearing ring (43) are both inserted into the shaft (22) by interference fit.

9. The track chassis roller assembly (17) of claim 1, wherein, The first radial inner bearing ring (42) and the second radial inner bearing ring (43) are slidably inserted into the shaft (22).

10. The track chassis roller assembly (17) of any one of claims 1-3, wherein, The roller body (18) includes a third annular recess (51) along the radial inner surface (20); a third stop ring (52) is inserted into the third annular recess (51) and the third stop ring (52) acts on the radial outer bearing ring (39).

11. The track chassis roller assembly (17) of any one of claims 1-3, wherein, The roller body (18) includes a shoulder (46) disposed on the radial inner surface (20); the radial outer bearing ring (39) abuts against the shoulder (46).

12. The track chassis roller assembly (17) of claim 10, wherein, The roller body (18) includes a fourth annular recess (53) along the radial inner surface (20); a fourth stop ring (54) is inserted into the fourth annular recess (53) and the fourth stop ring (54) is opposite to the third stop ring (52) inserted into the third annular recess (51) and acts on the radial outer bearing ring (39).

13. The track chassis roller assembly (17) of claim 12, wherein, The radial outer bearing ring (39) is slidably inserted into the inner cavity (19) of the roller body (18).

Images